Antitumor effect of the idiotypic cascade induced by an antibody encapsulated in poly(d,l-lactide-co-glycolide) microspheres

A major difficulty encountered during development of antibody vaccines is t heir weak immunogenicity. In this study, a monoclonal antibody CS20.5 to hu man breast cancer antigen CA15.3 was coencapsulated in poly (d,l-lactide-co -glycolide) microspheres with monophosphoryl lipid A. The antitumor effect of this formulation was investigated in a murine model. The induced Ab2 bio logically mimics antigen as it competed with CA15.3 for the same idiotope o n Abl. AW induction was also observed. After five sequential administration s of encapsulated antibody, mice showed statistically significant tumor reg ression. These results indicate that this formulation may serve as a potent ial treatment for breast cancer.